Storage virtualization is one of key techniques in cloud storage technology. Storage virtualization enables unified management of different storage techniques and different interfaces by a virtualization device, where a user device only needs to initiate a request to the virtualization device without knowing details of each physical storage device. The virtualization device takes full charge in handling requests from user devices, thus management of the storage network is simplified.
Storage virtualization at present includes two solutions: in-band virtualization and out-band virtualization. FIG. 1A is a schematic illustrating a network structure of in-band virtualization according to the prior art, and FIG. 1B is a schematic illustrating a network structure of out-band virtualization according to the prior art.
According to in-band virtualization, a virtualization device serves as an initiator of storage devices being virtualized, and the storage devices serve as targets of the virtualization device. An application server regards the virtualization device as the target. The virtualization device provides interfaces directly to external devices, and stores received to-be-stored data into the storage devices.
According to out-band virtualization, the virtualization device only provides control functions. Network device also provide part of the control functions. The application server will see a virtualized target. Service flows to be stored will not flow through the virtualization device, but be stored into the storage devices by the network device.